• The Transactions of The Korean Institute of Electrical Engineers
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• v.62 no.4
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• pp.502-509
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• 2013

It presents an efficient switching pattern, which expects a reduction of switching losses in a cascaded H-bridge PWM multilevel inverter. By the proposed switching scheme, the lower H-bridge module operates at low frequency of 60[Hz] because it assigns to transfer most load power. The upper H-bridge module operates at high frequency of PWM switching to improve THD of output voltage. The proposed switching pattern applies to cascaded H-bridge multilevel inverter with PD, APOD, bipolar, and unipolar switching methods. By computer-aided simulations, we verify the validity of the proposed switching scheme. Finally, we prove that the proposed PD and APOD switching patterns are better than those of the conventional one in efficiency.

• The Transactions of the Korean Institute of Power Electronics
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• v.3 no.3
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• pp.191-198
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• 1998

This paper presents a new current control method to reduce the torque ripple due to phase commutation, when the unipolar PWM method is applied for the phase current control of brushless DC motor. Phase commutation bring about an instantaneous change in the average voltage of conducting phase so that current undulates, and this undulating current generates torque ripple. In this paper, we analyze average voltage variations of conducting phase in commutation period with PWM pattern and design current controller to compensate average variations. In addition, we prove the validity of proposed method by experimental results.

• The Transactions of the Korean Institute of Power Electronics
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• v.20 no.2
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• pp.193-199
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• 2015

This paper proposes a regeneration braking algorithm for Brushless DC (BLDC) motor system. The unipolar switching method has a limitation about the regeneration braking when the BLDC motor is operated in the low speed region. The proposed algorithm alternatively utilizes the unipolar and bipolar switching method to implement the regeneration braking for overall speed range. The bipolar switching method is used when the BLDC motor is operated in the low speed region. The switching transition point is determined by analyzing the unipolar and bipolar switching during the regeneration braking. The effectiveness of proposed algorithm is verified by using the experimental results.

• The Journal of the Korea institute of electronic communication sciences
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• v.8 no.9
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• pp.1307-1312
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• 2013

In this paper, alkaline or acidic solution, in particular the principle of electrolysis to oxidize the metal surface to form a device isolation film is developed. In the past, mainly in the form of pulse voltage is applied to the anode only a unipolar method, but in this paper by using the H-bridge to the amount of the positive (+) voltage and the negative supply voltage, alternating voltage polarity devices were fabricated according to the characteristics of metal specimens with different electrical conditions to form an oxide film on the device was developed. Supply current variable was used for the PWM modulation, (+) and (-) polarity change of the H-bridge bipolar pulse voltage to supply the was that. As a result, a more uniform pores with unipolar film was formed.

• Journal of Electrical Engineering and Technology
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• v.12 no.5
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• pp.1835-1841
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• 2017

An improved single-phase full-bridge zero-voltage-switching inverter using a subtractive coupled magnetics is proposed in this paper. The proposed topology overcomes several drawbacks of the conventional ARCPI zero-voltage-switching inverter including two bulky capacitors which can cause problems such as the need for a protection circuit and voltage fluctuation of split capacitors. Also the proposed topology can reduce the number of devices required for ZVS through a simplified auxiliary circuit, thus achieving low cost and small volume and is applicable a modified unipolar PWM scheme. Detail mode analysis and design considerations are provided for optimal efficiency. In the end, the effectiveness and feasibility of the proposed topology are verified experimentally under various conditions.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.48 no.9
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• pp.490-497
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• 1999

This paper presents a novel current control method to reduce the current ripple due to commutation in brushless DC motor fed with unipolar PWM voltage source inverter. The proposed current control method can reduce the current ripple due to commutation in high speed range where the DC link voltage of the inverter is less than four times of the phase back-emf. The effectiveness of the proposed current control method is verified with digital simulations and experiments on the 250W brushless DC motor drive systems.

• Journal of IKEEE
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• v.26 no.4
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• pp.584-589
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• 2022

For DC-AC power conversion from a high-voltage photovoltaic panel to a single-phase grid, the two-stage transformerless inverter with a buck-boost converter followed by a full-bridge inverter is widely used. To avoid an excessive leakage current due to the large parasitic capacitance of the photovoltaic panel, the full-bridge inverter can only adopt the bipolar PWM which results in much higher power loss compared to the unipolar PWM. In order to overcome such a poor efficiency, this paper proposes a new topology in which an IGBT and a diode for circuit isolation are added to the buck-boost converter. The proposed circuit isolation method allows the unipolar PWM in the full-bridge inverter without any increase in the leakage current so that the overall efficiency can be improved. The validity of the proposed solution is verified by computer simulation and power loss calculation.

• The Journal of the Korea institute of electronic communication sciences
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• v.6 no.3
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• pp.355-362
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• 2011

In this paper, we developed the equipment to forming the insulation film which there are operated an electrolysis principles in particular solution. In the earlier, there are supplied the anode by unipolar voltage with pulse, in this paper, there are supplied the anode by bipolar voltage with pulse, alternately. And then, we examinate the system that there are developed the bipolar anodizing equipment using H-bridge. There are modulated pulse width for the variable current. In the results, we obtained the results of the uniform film surface that compared with the unipolar anodizing.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.4 no.1
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• pp.283-288
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• 2000

This paper proposes a novel Pulse Width Modulation (PWM) method for microprocessor implementation of full-bridge PWM inverters. In the method, the period of unipolar full-bridge inverters is divided equally into the frequency modulation ratio and the reference fundamental amplitude and the inverter output fundamental amplitude are compared. Using this method, the turn-on time computation of each interval is very favored for the microprocessor implementation. The harmonic analysis shows that the harmonics can be ignored when the modulation ratio is enough large. The simulation and experimental results show the effectiveness of the proposed algorithms.

• Proceedings of the KIPE Conference
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• 2014.11a
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• pp.33-34
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• 2014

In this paper, the inverter switch losses of BLDC motor for three types of PWM method and power devices was analyzed. When BLDC motor is driven at low currents, inverter switch losses for MOSFET is low because MOSFET operates like resistance. But, inverter switch losses for IGBT is higher than MOSFET due to its large turn-off losses. For low power inverter with MOSFET, the power losses of unified PWM is lower than that of unipolar and bipolar PWM.